Chap. VII. NEUTER INSECTS. 237 



having been born with some slight profitable modifi- 

 cation of structure, this being inherited by its offspring, 

 which again varied and were again selected, and so 

 onwards. But with the working ant we have an insect 

 differing greatly from its parents, yet absolutely sterile ; 

 so that it could never have transmitted successively 

 acquired modifications of structure or instinct to its pro- 

 geny. It may well be asked how is it possible to recon- 

 cile this case with the theory of natural selection ? 



First, let it be remembered that we have innumerable 

 instances, both in our domestic productions and in those 

 in a state of nature, of all sorts of differences of struc- 

 ture which have become correlated to certain ages, and 

 to either sex. We have differences correlated not only 

 to one sex, but to that short period alone when the re- 

 productive system is active, as in the nuptial plumage of 

 many birds, and in the hooked jaws of the male salmon. 

 We have even slight differences in the horns of different 

 breeds of cattle in relation to an artificially imperfect 

 state of the male sex ; for oxen of certain breeds have 

 longer horns than in other breeds, in comparison with 

 the horns of the bulls or cows of these same breeds. 

 Hence I can see no real difficulty in any character 

 having become correlated with the sterile condition of 

 certain members of insect-communities : the difficulty 

 lies in understanding how such correlated modifications 

 of structure could have been slowly accumulated by 

 natural selection. 



This clirficulty, though appearing insuperable, is 

 lessened, or, as I believe, disappears, when it is re- 

 membered that selection may be applied to the family, 

 as well as to the individual, and may thus gain the 

 desired end. Thus, a well-flavoured vegetable is cooked, 

 and the individual is destroyed ; but the horticulturist 

 sows seeds of the same stock, and confidently expects to 



